PHILADELPHIA (CBS) — The ten-year-old, critically ill Delaware County girl whose desperate search for a donor lung captured national attention has undergone a successful surgery today at Children’s Hospital of Philadelphia after a donor lung became available.

The family of Sarah Murnaghan of Newtown Square, Pa. says the six-hour surgery went smoothly and Sarah did extremely well.

WATCH: Family Gives Update Following Sarah’s Surgery

News that a lung had been found, and that gravely ill Sarah would be undergoing transplant surgery, was posted late Wednesday morning on the family’s Facebook page.

Janet Murnaghan, Sarah’s mother, disclosed that a donor — whom she called a “hero” — had been found and that the family was overwhelmed with emotions.

Sarah, who is suffering with end-stage cystic fibrosis, was placed into the adult donor line by order of a federal judge here in Philadelphia last week after he heard a plea from the family. She had been on the pediatric organ donor list for a lung for 18 months, but none became available.

Janet confirms the transplant team told her that pieces of the lungs from the donor were being implanted in her daughter’s chest. Janet says she knows nothing about the donor other than that the person is over 12.

The double lung transplant surgery started at 12:30 p.m. It’s a dangerous and difficult surgery that can take six to 12 hours.

With sirens blaring, the donated lungs arrived from an undisclosed location at 3 p.m.

About two hours later, Sarah Murnaghan’s mother told 3 On Your Side that the family is still waiting in the lounge, and hasn’t been updated on how the surgery is going. But she says the lungs came just in time for Sarah. Her condition was deteriorating rapidly. Her mom says the hardest part of the surgery is going to be getting her lungs out because they were so badly damaged and scarred.

CBS 3’s Stephanie Stahl asked Janet, “When you finally heard this transplant was going to happen what did you think?”

“We were making a lot of noise. We were really excited. This is an amazing blessing. This family saved her life,” she replied.

Janet says Sarah was in a medically induced coma and on a respirator since Saturday, and her prognosis without a transplant was grave.

U.S. Senator Bob Casey (D-PA) released the following statement:

“My thoughts and prayers are with Sarah Murnaghan and her family this afternoon. My heart goes out to the family of the donor and I thank them for giving Sarah – and potentially other organ transplant candidates – another chance at life.”

U.S. Senator Pat Toomey (R-PA) also reacted to the news:

“I am deeply grateful to the organ donor and his or her family for the potentially life-saving gift to Sarah.”

Congressman Patrick Meehan (PA-07) released a statement:

“I’m delighted to hear that Sarah will receive the life-saving lung transplant that she so desperately needs. She is one of the most courageous fighters I’ve ever seen, and she has an army of support behind her as she undergoes this very difficult surgery. I send my thoughts and prayers to her, her family, and the talented doctors and staff at CHOP that are caring for her.

“We must also recognize that Sarah’s chance at life comes through a gift of enormous generosity from someone else, and we should keep that person and their family in our thoughts and prayers as well. This demonstrates the huge importance of the life-saving gift of organ donation.”

Janet Murnaghan asked for prayers for Sarah and her surgical team. She called today “the start of Sarah’s new beginning and new life.”

We have no information about the donor, other than the lungs are very healthy and good in shape. Once Sarah makes it through surgery, her biggest risk for complications will be from rejection and infection.